U.S. patent application number 12/811327 was filed with the patent office on 2010-12-16 for method and an apparatus for processing an audio signal.
This patent application is currently assigned to LG ELECTRONICS INC.. Invention is credited to Yang Won Jung, Hyen-O Oh.
Application Number | 20100316230 12/811327 |
Document ID | / |
Family ID | 40824518 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100316230 |
Kind Code |
A1 |
Oh; Hyen-O ; et al. |
December 16, 2010 |
METHOD AND AN APPARATUS FOR PROCESSING AN AUDIO SIGNAL
Abstract
A method of processing an audio signal is disclosed. The present
invention includes receiving a downmix signal including at least
one object signal and object information extracted when the downmix
signal is generated, receiving mix information for controlling the
object signal, generating one of downmix processing information and
multi-channel information using the object information and the mix
information according to an output mode, and if the downmix
processing information is generated, generating an output signal by
applying the downmix processing information to the downmix signal,
wherein the downmix signal corresponds to a mono signal, wherein
the output signal corresponds to a stereo signal generated by
applying a decorrelator to the downmix signal, and wherein the
multi-channel information corresponds to information for upmixing
the downmix signal into a multi-channel signal.
Inventors: |
Oh; Hyen-O; (Gyeonggi-do,
KR) ; Jung; Yang Won; (Seoul, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
40824518 |
Appl. No.: |
12/811327 |
Filed: |
December 31, 2008 |
PCT Filed: |
December 31, 2008 |
PCT NO: |
PCT/KR2008/007863 |
371 Date: |
June 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61018488 |
Jan 1, 2008 |
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61018489 |
Jan 1, 2008 |
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61019821 |
Jan 8, 2008 |
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Current U.S.
Class: |
381/80 |
Current CPC
Class: |
G10L 19/008 20130101;
H04S 3/008 20130101; H04S 2400/11 20130101; H04S 2420/03 20130101;
G10L 19/20 20130101 |
Class at
Publication: |
381/80 |
International
Class: |
H04B 3/00 20060101
H04B003/00 |
Claims
1. A method of processing an audio signal, comprising: receiving a
downmix signal including at least one object signal, and object
information extracted when the downmix signal is generated;
receiving mix information for controlling the object signal;
generating one of downmix processing information and multi-channel
information using the object information and the mix information
according to an output mode; and if the downmix processing
information is generated, generating an output signal by applying
the downmix processing information to the downmix signal, wherein
the downmix signal corresponds to a mono signal, wherein the output
signal corresponds to a stereo signal generated by applying a
decorrelator to the downmix signal, and wherein the multi-channel
information corresponds to information for upmixing the downmix
signal into a plurality of channel signals.
2. The method of claim 1, wherein each of the downmix signal and
the output signal corresponds to a signal on a time domain.
3. The method of claim 1, wherein the generating the output signal
comprises: generating a subband signal by decomposing the downmix
signal; generating two subband signals by processing the subband
signal using the downmix processing information; and generating the
output signal by synthesizing the two subband signals
respectively.
4. The method of claim 3, wherein the generating the two subband
signals comprises: generating a decorrelated signal by
decorrelating the subband signal; and generating the two subband
signals by processing the decorrelated signal and the subband
signal using the downmix processing information.
5. The method of claim 1, wherein the downmix processing
information includes a binaural parameter, and wherein the output
signal corresponds to a binaural signal.
6. The method of claim 1, further comprising generating a plurality
of channel signals by upmixing the downmix signal using the
multi-channel information if the multi-channel information is
generated.
7. The method of claim 1, wherein the output mode is determined
according to a speaker channel number and wherein the speaker
channel number is based on one of device information and the mix
information.
8. An apparatus for processing an audio signal, comprising: a
demultiplexer receiving a downmix signal including at least one
object signal, and object information extracted when the downmix
signal is generated; an information generating unit generating one
of downmix processing information and multi-channel information
using the object information and mix information for controlling
the object signal according to an output mode; and a downmix
processing unit, if the downmix processing information is
generated, generating an output signal by applying the downmix
processing information to the downmix signal, wherein the downmix
signal corresponds to a mono signal, wherein the output signal
corresponds to a stereo signal generated by applying a decorrelator
to the downmix signal, and wherein the multi-channel information
corresponds to information for upmixing the downmix signal into a
plurality of channel signals.
9. The apparatus of claim 8, wherein the downmix signal and the
output signal correspond to a signal on a time domain.
10. The apparatus of claim 8, wherein the downmix processing unit
comprises: a subband decomposing unit generating a subband signal
by decomposing the downmix signal; an M2M processing unit
generating two subband signals by processing the subband signal
using the downmix processing information; and a synthesizing unit
generating the output signal by synthesizing the two subband
signals respectively.
11. The apparatus of claim 10, wherein the M2S processing unit
further comprises a decorrelator generating a decorrelated signal
by decorrelating the subband signal, and wherein the synthesizing
unit generates the two subband signals by processing the
decorrelated signal and the subband signal using the downmix
processing information.
12. The apparatus of claim 8, wherein the downmix processing
information includes a binaural parameter, and wherein the output
signal corresponds to a binaural signal.
13. The apparatus of claim 8, further comprising a multi-channel
decoder generating a plurality of channel signals by upmixing the
downmix signal using the multi-channel information if the
multi-channel information is generated.
14. The apparatus of claim 8, wherein the output mode is determined
according to a speaker channel number and wherein the speaker
channel number is based on one of device information and the mix
information.
15. A computer-readable recording medium comprising a program
stored therein, the program provided for executing a method of
processing an audio signal, the method comprising: receiving a
time-domain downmix signal including at least one object signal,
and object information extracted when the downmix signal is
generated; receiving mix information for controlling the object
signal; generating one of downmix processing information and
multi-channel information using the object information and the mix
information according to an output mode; and if the downmix
processing information is generated, generating an output signal by
applying the downmix processing information to the downmix signal,
wherein the downmix signal corresponds to a mono signal, wherein
the output signal corresponds to a stereo signal generated by
applying a decorrelator to the downmix signal, and wherein the
multi-channel information corresponds to information for upmixing
the downmix signal into a plurality of channel signals.
Description
TECHNICAL FIELD
[0001] The present invention relates to an apparatus for processing
an audio signal and method thereof. Although the present invention
is suitable for a wide scope of applications, it is particularly
suitable for processing an audio signal received via a digital
medium, a broadcast signal and the like.
BACKGROUND ART
[0002] Generally, in the process for downmixing a plurality of
objects into a mono or stereo signal, parameters are extracted from
the object signals, respectively. These parameters are usable for a
decoder. Panning and gain of each of the objects is controllable by
a user selection.
DISCLOSURE OF THE INVENTION
Technical Problem
[0003] However, in order to control each object signal, each source
contained in a downmix should be appropriately positioned or
panned.
[0004] Moreover, in order to provide backward compatibility
according to a channel-oriented decoding scheme, an object
parameter should be converted to a multi-channel parameter for
upmixing.
Technical Solution
[0005] Accordingly, the present invention is directed to an
apparatus for processing an audio signal and method thereof that
substantially obviate one or more of the problems due to
limitations and disadvantages of the related art.
[0006] An object of the present invention is to provide an
apparatus for processing an audio signal and method thereof, by
which a mono signal, a stereo signal and a multi-channel signal can
be outputted by controlling gain and panning of an object.
[0007] Another object of the present invention is to provide an
apparatus for processing an audio signal and method thereof, by
which a mono signal and a stereo signal can be outputted from a
downmix signal without performing a complicated scheme of a
multi-channel decoder.
[0008] A further object of the present invention is to provide an
apparatus for processing an audio signal and method thereof, by
which distortion of a sound quality can be prevented in case of
adjusting a gain of a vocal or background music with a considerable
width.
Advantageous Effects
[0009] Accordingly, the present invention provides the following
effects or advantages.
[0010] First of all, the present invention is able to control gain
and panning of an object without limitation.
[0011] Secondly, the present invention is able to control gain and
panning of an object based on a user-selection.
[0012] Thirdly, in case that an output mode is a mono or stereo,
the present invention generates an output signal without performing
a complicated scheme of a multi-channel decoder, thereby
facilitating implementation and lowering complexity.
[0013] Fourthly, in case that one or two speakers are provided for
such a device as a mobile device, the present invention is able to
control gain and panning of an object for a downmix signal without
a codec coping with a multi-channel decoder.
[0014] Fifthly, in case that either a vocal or background music is
completely suppressed, the present invention is able to prevent
distortion of a sound quality according to gain adjustment.
[0015] Sixthly, in case that at least two independent objects
(stereo channel or several vocal signals) such as a vocal and the
like exist, the present invention is able to prevent distortion of
a sound quality according to gain adjustment.
DESCRIPTION OF DRAWINGS
[0016] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0017] In the drawings:
[0018] FIG. 1 is a block diagram of an apparatus for processing an
audio signal according to an embodiment of the present invention
for generating a mono/stereo signal;
[0019] FIG. 2 is a detailed block diagram for a first example of a
downmix processing unit shown in FIG. 1;
[0020] FIG. 3 is a detailed block diagram for a second example of a
downmix processing unit shown in FIG. 1;
[0021] FIG. 4 is a block diagram of an apparatus for processing an
audio signal according to one embodiment of the present invention
for generating a binaural signal;
[0022] FIG. 5 is a detailed block diagram of a downmix processing
unit shown in FIG. 4;
[0023] FIG. 6 is a block diagram of an apparatus for processing an
audio signal according to another embodiment of the present
invention for generating a binaural signal;
[0024] FIG. 7 is a block diagram of an apparatus for processing an
audio signal according to one embodiment of the present invention
for controlling an independent object;
[0025] FIG. 8 is a block diagram of an apparatus for processing an
audio signal according to another embodiment of the present
invention for controlling an independent object;
[0026] FIG. 9 is a block diagram of an apparatus for processing an
audio signal according to a first embodiment of the present
invention for processing an enhanced object;
[0027] FIG. 10 is a block diagram of an apparatus for processing an
audio signal according to a second embodiment of the present
invention for processing an enhanced object; and
[0028] FIG. 11 and FIG. 12 are block diagrams of an apparatus for
processing an audio signal according to a third embodiment of the
present invention for processing an enhanced object.
BEST MODE
[0029] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims thereof as well as the
appended drawings.
[0030] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described, a method of processing an audio signal according to the
present invention includes receiving a downmix signal including at
least one object signal and object information extracted when the
downmix signal is generated, receiving mix information for
controlling the object signal, generating one of downmix processing
information and multi-channel information using the object
information and the mix information according to an output mode,
and if the downmix processing information is generated, generating
an output signal by applying the downmix processing information to
the downmix signal, wherein the downmix signal and the output
signal correspond to a mono signal and wherein the multi-channel
information corresponds to information for upmixing the downmix
signal into a plurality of channel signals.
[0031] According to the present invention, the downmix signal and
the output signal correspond to a signal on a time domain.
[0032] According to the present invention, the generating the
output signal includes generating a subband signal by decomposing
the downmix signal, processing the subband signal using the downmix
processing information, and generating the output signal by
synthesizing the subband signal.
[0033] According to the present invention, the output signal
includes a signal generated by decorrelating the downmix
signal.
[0034] According to the present invention, the method further
includes generating the plurality of the channel signals by
upmixing the downmix signal using the multi-channel information if
the multi-channel information is generated.
[0035] According to the present invention, the output mode is
determined according to a speaker channel number and the speaker
channel number is based on one of device information and the mix
information.
[0036] According to the present invention, the mix information is
generated based on at least one of object position information,
object gain information and playback configuration information.
[0037] To further achieve these and other advantages and in
accordance with the purpose of the present invention, an apparatus
for processing an audio signal includes a demultiplexer receiving a
downmix signal including at least one object signal, and object
information extracted when the downmix signal is generated, an
information generating unit generating one of downmix processing
information and multi-channel information using the object
information and mix information for controlling the object signal
according to an output mode, and a downmix processing unit, if the
downmix processing information is generated, generating an output
signal by applying the downmix processing information to the
downmix signal, wherein the downmix signal and the output signal
correspond to a mono signal and wherein the multi-channel
information corresponds to information for upmixing the downmix
signal into a plurality of channel signals.
[0038] According to the present invention, the downmix processing
unit includes a subband decomposing unit generating a subband
signal by decomposing the downmix signal, an M2M processing unit
processing the subband signal using the downmix processing
information, and a subband synthesizing unit generating the output
signal by synthesizing the subband signal.
[0039] To further achieve these and other advantages and in
accordance with the purpose of the present invention, a method of
processing an audio signal according to the present invention
includes receiving a downmix signal including at least one object
signal and object information extracted when the downmix signal is
generated, receiving mix information for controlling the object
signal, generating one of downmix processing information and
multi-channel information using the object information and the mix
information according to an output mode, and if the downmix
processing information is generated, generating an output signal by
applying the downmix processing information to the downmix signal,
wherein the downmix signal corresponds to a mono signal, wherein
the output signal corresponds to a stereo signal generated by
applying a decorrelator to the downmix signal, and wherein the
multi-channel information corresponds to information for upmixing
the downmix signal into a multi-channel signal.
[0040] According to the present invention, the downmix signal and
the output signal correspond to a signal on a time domain.
[0041] According to the present invention, the generating the
output signal includes generating a subband signal by decomposing
the downmix signal, generating two subband signals by processing
the subband signal using the downmix processing information, and
generating the output signal by synthesizing the two subband
signals respectively.
[0042] According to the present invention, the generating the two
subband signals includes generating a decorrelated signal by
decorrelating the subband signal and generating the two subband
signals by processing the decorrelated signal and the subband
signal using the downmix processing information.
[0043] According to the present invention, the downmix processing
information includes a binaural parameter and the output signal
corresponds to a binaural signal.
[0044] According to the present invention, the method further
includes generating a plurality of channel signals by upmixing the
downmix signal using the multi-channel information if the
multi-channel information is generated.
[0045] According to the present invention, the output mode is
determined according to a speaker channel number and the speaker
channel number is based on one of device information and the mix
information.
[0046] To further achieve these and other advantages and in
accordance with the purpose of the present invention, an apparatus
for processing an audio signal includes a demultiplexer receiving a
downmix signal including at least one object signal, a time domain
downmix signal , and object information extracted when the downmix
signal is generated, an information generating unit generating one
of downmix processing information and multi-channel information
using mix information for controlling the object signal and the
object information according to an output mode, and a downmix
processing unit, if the downmix processing information is
generated, generating an output signal by applying the downmix
processing information to the downmix signal, wherein the downmix
signal corresponds to a mono signal, wherein the output signal
corresponds to a stereo signal generated by applying a decorrelator
to the downmix signal, and wherein the multi-channel information
corresponds to information for upmixing the downmix signal into a
plurality of channel signals.
[0047] To further achieve these and other advantages and in
accordance with the purpose of the present invention, a method of
processing an audio signal according to the present invention
includes receiving a downmix signal including at least one object
signal and object information extracted when the downmix signal is
generated, receiving mix information including mode selection
information, the mix information for controlling the object signal,
bypassing the downmix signal or extracting a background object and
at least one independent object from the downmix signal based on
the mode selection information, and if the downmix signal is
bypassed, generating multi-channel information using the object
information and the mix information, wherein the downmix signal
corresponds to a mono signal and wherein the mode selection
information includes information indicating which one of modes
including a normal mode, a mode for controlling the background
object, and a mode for controlling the at least one independent
object.
[0048] According to the present invention, the method further
includes receiving enhanced object information, wherein the at
least one independent object is extracted from the downmix signal
using the enhanced object information.
[0049] According to the present invention, the enhanced object
information corresponds to a residual signal.
[0050] According to the present invention, the at least one
independent object corresponds to an object based signal and the
background object corresponds to a mono signal.
[0051] According to the present invention, the stereo output signal
is generated if the mode selection mode corresponds to the normal
mode. And, the background object and the at least one independent
object are extracted if the mode selection mode corresponds to one
of the mode for controlling the background object and the mode for
controlling the at least one independent object.
[0052] According to the present invention, the method further
includes, if the background object and the at least one independent
object are extracted from the downmix signal, generating at least
one of first multi-channel information for controlling the
background object and second multi-channel information for
controlling the at least one independent object.
[0053] To further achieve these and other advantages and in
accordance with the purpose of the present invention, an apparatus
for processing an audio signal includes a demultiplexer receiving a
downmix signal including at least one object signal and object
information extracted when the downmix signal is generated, an
object transcoder bypassing the downmix signal or extracting a
background object and at least one independent object from the
downmix signal, based on mode selection information included in mix
information for controlling the object signal, and a multi-channel
decoder, if the downmix signal is bypassed, generating
multi-channel information using the object information and the mix
information, wherein the downmix signal corresponds to a mono
signal, wherein the output signal corresponds to a stereo signal
generated by applying a decorrelator to the downmix signal, and
wherein the mode selection information includes information
indicating which one of modes including a normal mode, a mode for
controlling the background object, and a mode for controlling the
at least one independent object.
[0054] To further achieve these and other advantages and in
accordance with the purpose of the present invention, a method of
processing an audio signal according to the present invention
includes receiving a downmix signal including at least one object
signal and object information extracted when the downmix signal is
generated, receiving mix information including mode selection
information, the mix information for controlling the object signal,
and generating a stereo output signal using the downmix signal or
extracting a background object and at least one independent object
from the downmix signal based on the mode selection information,
wherein the downmix signal corresponds to a mono signal, wherein
the stereo output signal corresponds to a time-domain signal
including a signal generated by decorrelating the downmix signal,
and wherein the mode selection information includes information
indicating which one of modes including a normal mode, a mode for
controlling the background object, and a mode for controlling the
at least one independent object.
[0055] According to the present invention, the method further
includes receiving enhanced object information, wherein the at
least one independent object is extracted from the downmix signal
using the enhanced object information.
[0056] According to the present invention, the enhanced object
information corresponds to a residual signal.
[0057] According to the present invention, the at least one
independent object corresponds to an object based signal and the
background object corresponds to a mono signal.
[0058] According to the present invention, the stereo output signal
is generated if the mode selection mode corresponds to the normal
mode. And, the background object and the at least one independent
object are extracted if the mode selection mode corresponds to one
of the mode for controlling the background object and the mode for
controlling the at least one independent object.
[0059] According to the present invention, the method further
includes, if the background object and the at least one independent
object are extracted from the downmix signal, generating at least
one of first multi-channel information for controlling the
background object and second multi-channel information for
controlling the at least one independent object.
[0060] To further achieve these and other advantages and in
accordance with the purpose of the present invention, an apparatus
for processing an audio signal includes a demultiplexer receiving a
downmix signal including at least one object signal and object
information extracted when the downmix signal is generated and an
object transcoder generating a stereo output signal using the
downmix signal or extracting a background object and at least one
independent object from the downmix signal based on mode selection
information included in mix information for controlling the object
signal, wherein the downmix signal corresponds to a mono signal,
wherein the stereo output signal corresponds to a time-domain
signal including a signal generated by decorrelating the downmix
signal, and wherein the mode selection information includes
information indicating which one of modes including a normal mode,
a mode for controlling the background object, and a mode for
controlling the at least one independent object.
[0061] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
MODE FOR INVENTION
[0062] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. First of all,
terminologies in the present invention can be construed as the
following references. And, terminologies not disclosed in this
specification can be construed as the following meanings and
concepts matching the technical idea of the present invention.
[0063] Specifically, `information` in this disclosure is the
terminology that generally includes values, parameters,
coefficients, elements and the like and its meaning can be
construed as different occasionally, by which the present invention
is not limited.
[0064] An object has the concept including both an object based
signal and a channel based signal. Occasionally, an object can
include an object based signal only.
[0065] In case that a mono downmix signal is received, the present
invention intends to describe various processes for processing a
mono downmix signal. First of all, a method of generating a
mono/stereo signal or a plurality of channel signals from a mono
downmix signal if necessary shall be explained with reference to
FIGS. 1 to 3. Secondly, a method of generating a binaural signal
from a mono downmix signal (or a stereo downmix signal) shall be
explained with reference to FIGS. 4 to 6. Thirdly, various
embodiments for a method of controlling an independent object
signal (or a mono background signal) contained in a mono downmix
are explained with reference to FIGS. 7 to 12.
[0066] 1. Generation of Mono/Stereo Signal
[0067] FIG. 1 is a block diagram of an apparatus for processing an
audio signal according to an embodiment of the present invention
for generating a mono/stereo signal.
[0068] Referring to FIG. 1, an apparatus 100 for processing an
audio signal according to an embodiment of the present invention
includes a demultiplexer 110, an information generating unit 120,
and a downmix processing unit 130. The audio signal processing
apparatus 100 can further include a multi-channel decoder 140.
[0069] The demultiplexer 110 receives object information (OI) via a
bitstream. The object information (OI) is the information on
objects contained within a downmix signal and is able to include
object level information, object correlation information, and the
like. The object information (OI) is able to contain an object
parameter (OP) that is a parameter indicating an object
characteristic.
[0070] The bitstream further contains a downmix signal (DMX). The
demultiplexer 110 is able to further extract the downmix signal
(DMX) from this bitstream. The downmix signal (DMX) is the signal
generated from downmixing at least one object signal and may
correspond to a signal on a time domain. The downmix signal (DMX)
may be a mono signal or a stereo signal. In the present embodiment,
the downmix signal (DMX) is a mono signal for example.
[0071] The information generating unit 120 receives the object
information (OI) from the demultiplexer 110. The information
generating unit 120 receives mix information (MXI) from a user
interface. The information generating unit 120 receives output mode
information (OM) from the user interface or device. The information
generating unit 120 is able to further receive HRTF (head-related
transfer function) parameter from HRTF DB.
[0072] In this case, the mix information (MXI) is the information
generated based on object position information, object gain
information, playback configuration information and the like. The
object position information is the information inputted for a user
to control a position or panning of each object. The object gain
information is the information inputted for a user to control a
gain of each object. Specifically, the object position information
or the object gain information may be the one selected from preset
modes. In this case, the preset mode is the value for presetting a
specific gain or position of an object in process of time. The
preset mode information can be a value received from another device
or a value stored in a device. Meanwhile, selecting one from at
least one or more preset modes (e.g., preset mode not in use,
preset mode 1, preset mode 2, etc.) can be determined by a user
input.
[0073] The playback configuration information is the information
containing the number of speakers, a position of speaker, ambient
information (virtual position of speaker) and the like. The
playback configuration information can be inputted by a user, can
be stored in advance, or can be received from another device.
[0074] The output mode information (OM) is the information on an
output mode. For instance, the output mode information (OM) can
include the information indicating how many signals are used for
output. This information indicating how many signals are used for
output can correspond to one of a mono output mode, a stereo output
mode, a multi-channel output mode and the like. Meanwhile, the
output mode information (OM) may be identical to the number of
speakers of the mix information (MXI). If the output mode
information (OM) is stored in advance, it is based on device
information. If the output mode information (OM) is inputted by a
user, it is based on user input information. In this case, the user
input information can be included in the mix information (MXI).
[0075] The information generating unit 120 generates one of downmix
processing information (DPI) and multi-channel information (MI)
using the object information (OI) and the mix information (MXI),
according to an output mode. In this case, the output mode is based
on the above-explained output mode information (OM). If the output
mode is a mono output or a stereo signal, the information
generating unit 120 generates the downmix processing information
(DPI). If the output mode is a multi-channel output, the
information generating unit 120 generates the multi-channel
information (MI). In this case, the downmix processing information
(DPI) is the information for processing a downmix signal (DMX), of
which details will be explained later. The multi-channel
information (MI) is the information for upmixing a downmix signal
(DMX) and is able to include channel level information, channel
correlation information and the like.
[0076] If the output mode is a mono output or a stereo output, the
downmix processing information (DPI) is generated only. This is
because the downmix processing unit 130 is able to generate a
time-domain mono signal or a time-domain stereo signal. Meanwhile,
if the output mode is a multi-channel output, the multi-channel
information (MI) is generated. This is because the multi-channel
decoder 140 can generate a multi-channel signal in case that an
input signal is a mono signal.
[0077] The downmix processing unit 130 generates a mono output
signal or a stereo output signal using the downmix processing
information (DPI) and the mono downmix (DMX). In this case, the
downmix processing information (DPI) is the information for
processing a downmix signal (DMX) and is to control gains and/or
pannings of objects contained in the downmix signal.
[0078] Meanwhile, the mono output signal or the stereo output
signal corresponds to the time-domain signal and may include a PCM
signal. In case of the mono output signal, the detailed
configuration of the downmix processing unit 130 will be explained
with reference to FIG. 2. In case of the stereo output signal, the
detailed configuration of the downmix processing unit 130 will be
explained with reference to FIG. 3.
[0079] Furthermore, the downmix processing information (DPI) can
include a binaural parameter. In this case, the binaural parameter
is the parameter for 3D effect and may be the information generated
by the information generating unit 120 using object information
(OI), mix information (MXI) and HRTF parameter. In case that the
downmix processing information (DPI) includes the binaural
parameter, the downmix processing unit 130 is able to output a
binaural signal. An embodiment for generating a binaural signal
will be explained in detail with reference to FIGS. 4 to 6
later.
[0080] If a stereo downmix signals received instead of a mono
downmix signal [not shown in the drawing], processing for modifying
a crosstalk of the downmix signal only is performed rather than a
time-domain output signal is generated. The processed downmix
signal can be handled by the multi-channel decoder 140 again. Yet,
the present invention is not limited by this processing.
[0081] If an output mode is a multi-channel output mode, the
multi-channel decoder 140 generates a multi-channel signal by
upmixing the downmix (DMX) using the multi-channel information. The
multi-channel decoder 140 can be implemented according to the
standard of MPEG Surround (IS)/IEC 23003-1), by which the present
invention is not limited.
[0082] FIG. 2 is a detailed block diagram for a first example of a
downmix processing unit shown in FIG. 1, which is an embodiment for
generating a mono output signal. FIG. 3 is a detailed block diagram
for a second example of a downmix processing unit shown in FIG. 1,
which is an example for generating a stereo output signal.
[0083] Referring to FIG. 2, a downmix processing unit 130A includes
a subband decomposing unit 132A, an M2M processing unit 134A and a
subband synthesizing unit 136A. The downmix processing unit 130A
generates a mono output signal from a mono downmix signal.
[0084] The subband decomposing unit 132A generates a subband signal
by decomposing a mono downmix signal (DMX). The subband decomposing
unit 132A is implemented with a hybrid filter bank and the subband
signal may correspond to a signal on hybrid QMF domain. The M2M
processing unit 134A processes the subband signal using downmix
processing information (DPI). In this case, M2M is an abbreviation
of mono-to-mono. The M2M processing unit 134A is able to use a
decorrelator to process the subband signal. The subband
synthesizing unit 136A generates a time-domain mono output signal
by synthesizing the processes subband signal. Moreover, the subband
synthesizing unit 136A can be implemented with a hybrid filter
bank.
[0085] Referring to FIG. 3, a downmix processing unit 132B includes
a subband decomposing unit 132B, an M2S processing unit 134B, a
first subband synthesizing unit 136B and a second subband
synthesizing unit 138B. The downmix processing unit 130B receives a
mono downmix signal and then generates a stereo output.
[0086] Like the former subband decomposing unit 132A shown in FIG.
2, the subband decomposing unit 132B generates a subband signal by
decomposing a mono downmix signal (DMX). Likewise, the subband
decomposing unit 132B can be implemented with a hybrid filter
bank.
[0087] The M2S processing unit 134B generates two subband signals
(first subband signal and second subband signal) by processing the
subband signal using downmix processing information (DPI) and a
decorrelator 135B. In this case, M2S is an abbreviation of
mono-to-stereo. If the decorrelator 135B is used, it is able to
raise a stereo effect by lowering correlation between right and
left channels.
[0088] Meanwhile, the decorrelator 135B sets the subband signal
inputted from the subband decomposing unit 132B to a first subband
signal and is then able to output a signal generated by
decorrelating the first subband signal as a second subband signal,
by which the present invention is not limited.
[0089] The first subband synthesizing unit 136B synthesizes the
first subband signal, and the second subband synthesizing unit 138B
synthesizes the second subband signal, whereby a time-domain stereo
output signal is generated.
[0090] Thus, in case that a mono downmix is inputted, an embodiment
of outputting a mono/stereo output via a downmix processing unit is
explained in the above description. In the following description, a
case of generating a binaural signal is explained.
[0091] 2. Generation of Binaural Signal
[0092] FIG. 4 is a block diagram of an apparatus for processing an
audio signal according to one embodiment of the present invention
for generating a binaural signal. FIG. 5 is a detailed block
diagram of a downmix processing unit shown in FIG. 4. FIG. 6 is a
block diagram of an apparatus for processing an audio signal
according to another embodiment of the present invention for
generating a binaural signal.
[0093] With reference to FIG. 4 and FIG. 5, one embodiment for
generating a binaural signal is explained. With reference to FIG.
6, another embodiment for generating a binaural signal is
explained.
[0094] Referring to FIG. 4, an audio signal processing apparatus
200 includes a demultiplexer 210, an information generating unit
220 and a downmix processing unit 230. In this case, like the
former demultiplexer 110 described with reference to FIG. 1, the
demultiplexer 210 extracts object information (OI) from a bitstream
and is able to further extract a downmix (DMX) from the bistream.
In this case, the downmix signal can be a mono signal or a stereo
signal.
[0095] The information generating unit 220 generates downmix
processing information containing a binaural parameter using the
object information (OI), mix information (MXI) and HRTF
information. In this case, the HRTF information can be the
information extracted from HRTF DB. And, the binaural parameter is
the parameter for bringing the virtual 3D effect.
[0096] The downmix processing unit 230 outputs a binaural signal
using downmix processing information (DPI) that includes the
binaural parameter. Detailed configuration of the downmix
processing unit 230 is explained with reference to FIG. 5.
[0097] Referring to FIG. 5, a downmix processing unit 230A includes
a subband decomposing unit 232A, a binaural processing unit 234A
and a subband synthesizing unit 236A. The subband decomposing unit
232A generates one or twp subband signals by decomposing a downmix
signal. The binaural processing unit 234A processes the one or two
subband signals using downmix processing information (DPI)
containing a binaural parameter. The subband synthesizing unit 236A
generates a time-domain binaural output signal by synthesizing the
one or two subband signals.
[0098] Referring to FIG. 6, an audio signal processing apparatus
300 includes a demultiplexer 310 and an information generating unit
320. The audio signal processing apparatus 300 can further include
a multi-channel decoder 330.
[0099] The demultiplexer 310 extracts object information (OI) from
a bitstream and is able to further extract a downmix signal (DMX)
from the bitstream. The information generating unit 320 generates
multi-channel information (MI) using the object information (OI)
and mix information (MXI). In this case, the multi-channel
information (MI) is the information for upmixing the downmix signal
(DMX) and includes such a spatial parameter as channel level
information and channel correlation information. The information
generating unit 320 generates a binaural parameter using HRTF
parameter extracted from HRTF DB. The binaural parameter is the
parameter for brining the 3D effect and can include the HRTF
parameter itself. The binaural parameter is a time-invariant value
and can have a dynamic characteristic.
[0100] If the downmix signal is a mono signal, the multi-channel
information (MI) can further include gain information (ADG). In
this case, the gain information (ADG) is the parameter for
adjusting a downmix gain and is usable in controlling a gain for a
specific object. In case of a binaural output, upsampling or
downsampling for an object is necessary. It is preferable to use
the gain information (ADG). If the multi-channel decoder 330
follows the MPS Surround standard and the multi-channel information
(MI) needs to be configured according to MPEG surround syntax, it
is able to use the gain information (ADG) by setting
`bsArbitraryDownmix=1`.
[0101] If the downmix signal is a stereo signal, the audio signal
processing apparatus 300 can further include a downmix processing
unit (not shown in the drawing) for re-panning of right and left
cannels of a stereo downmix signal. Yet, in the binaural rendering,
cross-term of right and left channels can be generated by a
selection of HRTF parameter. Hence, an operation in the downmix
processing unit (not shown in the drawing) is not essential. If the
downmix signal is stereo and the multi-channel information (MI)
follows the MPS surround standard, it is preferably set to 5-2-5
configuration mode. And, it is preferably outputted by bypassing a
front left channel and a right front channel only. Besides, the
binaural parameter can be transferred in a manner that paths from
the right and left front channels to right and left outputs (total
four parameter sets) have valid values while the rest of values are
zero.
[0102] The multi-channel decoder 330 generates a binaural output
from the downmix signal using the multi-channel information (MI)
and the binaural parameter. In particular, the multi-channel
decoder 330 is able to generate a binaural output by applying a
combination of the spatial parameter included in the multi-channel
information and the binaural parameter to the downmix signal.
[0103] In the above description, the embodiments for generating a
binaural output are explained. Like the first embodiment, if a
binaural output is directly generated via a downmix processing
unit, a complicated scheme of a multi-channel decoder needs not to
be performed. Therefore, complexity can be lowered. Like the second
embodiment, if a multi-channel decoder is used, it is able to use a
function of the multi-channel decoder.
[0104] 3. Control of Independent Object (Karaoke Mode/a Cappella
Mode)
[0105] In the following description, a technique for controlling an
independent object or a background object by receiving a mono
downmix is explained.
[0106] FIG. 7 is a block diagram of an apparatus for processing an
audio signal according to one embodiment of the present invention
for controlling an independent object, and FIG. 8 is a block
diagram of an apparatus for processing an audio signal according to
another embodiment of the present invention for controlling an
independent object.
[0107] Referring to FIG. 7, a multi-channel decoder 410 of an audio
signal encoding apparatus 400 receives a plurality of channel
signals and then generates a mono downmix (DMXm) and a
multi-channel bitstream. In this case, a plurality of the channels
signals are multi-channel background objects (MBO).
[0108] For instance, the multi-channel background object (MBO) is
able to include a plurality of instrument signals configuring
background music. Yet, it is unable to know how many source signals
(e.g., instrument signals) are included. And, they are
uncontrollable per source signal. Although the background object
can be downmixed into a stereo channel, the present invention
intends to describe a background object downmixed into a mono
signal only.
[0109] An object encoder 420 generates a mono downmix (DMX) by
downmixing a mono background object (DMXm) and at least one object
signal (obj.sub.N) and also generates an object information
bitstream. In this case, the at least one object signal (or an
object based signal) is an independent object and can be called a
foreground object (FGO). For instance, if a background object is
accompaniment, an independent object (FGO) can correspond to a lead
vocal signal. Of course, if two independent objects exist, the can
correspond to a vocal signal of a singer 1 and a vocal signal of a
singer 2, respectively. And, the object encoder 420 is able to
further generate residual information.
[0110] The object encoder 420 is able to generate a residual in the
course of downmixing the mono background object (DMXm) and the
object signal (obj.sub.N) (i.e., independent object). This residual
is usable for a decoder to extract an independent object (or,
background object) from a downmix signal.
[0111] An object transcoder 510 of an audio signal decoding
apparatus 500 extracts at least one independent object or a
background object from the downmix (DMX) using enhanced object
information (e.g., residual), according to mode selection
information (MSI) included in mix information (MXI).
[0112] The mode selection information (MSI) includes the
information indicating whether a mode for controlling a background
object and at least one independent object is selected. Moreover,
the mode selection information (MSI) can include the information
indicating a prescribed mode corresponds to which one of modes
including a normal mode, a mode for controlling a background
object, and a mode for controlling at least one independent object.
For instance, if a background object is background music, a mode
for controlling a background object can correspond to `a cappella`
mode (or, solo mode). For instance, if an independent object is
vocal, a mode for controlling at least one independent object may
correspond to a karaoke mode. In other words, the mode selection
information can be the information indicating whether one of the
normal mode, the `a cappella` mode and the karaoke mode is
selected. Moreover, in case of the `a cappella` or karaoke mode,
information on gain adjustment can be further included. In summary,
if the mode selection information (MSI) is the `a cappella` or
karaoke mode, at least one independent object or a background
object is extracted from the downmix (DMX). In case of the normal
mode, the downmix signal can undergo bypass.
[0113] If an independent object is extracted, the object transcoder
510 generates a mixed mono downmix by mixing at least one
independent object and a background object using object information
(OI), mix information (MI) and the like. In this case, the object
information (OI) is the information extracted from the object
information bitstream and may be identical to that explained in the
foregoing description. And, the mix information (MXI) can be the
information for adjusting an object gain and/ or panning.
[0114] Meanwhile, the object transcoder 510 generates multi-channel
information (MI) using the multi-channel bitstream and/or the
object information bitstream. The multi-channel information (MI)
may be provided to control the background object or the at least
one independent object. In this case, the multi-channel information
can include at least one of first multi-channel information for
controlling the background object and second multi-channel
information for controlling the at least one independent
object.
[0115] And, a multi-channel decoder 520 generates an output signal
from a mono downmix mixed using the multi-channel information (MI)
or a bypassed mono downmix.
[0116] FIG. 8 is a diagram of another embodiment for independent
object generation.
[0117] Referring to FIG. 8, an audio signal processing unit 600
receives a mono downmix (DMX). The audio signal processing
apparatus 600 includes a downmix processing unit 610, a
multi-channel decoder 620, an OTN module 630 and a rendering unit
640.
[0118] The audio signal processing apparatus 600 determines whether
to input the downmix signal to the OTN module 630, according to
mode selection information (MSI). In this case, the mode selection
information may be identical to the former mode selection
information described with reference to FIG. 7.
[0119] If a current mode is a mode for controlling a background
object (MBO) or at least one independent object (FGO) according to
the mode selection information, the downmix signal is allowed to be
inputted to the OTN module 630. If a current mode is a normal mode
according to the mode selection information, the downmix signal
bypasses the OTN module 530 but is inputted to the downmix
processing unit 610 or the multi-channel decoder 620 according to
an output mode. In this case, the output mode is identical to the
output mode information (OM) described with reference to FIG. 1 and
may include the number of output speakers.
[0120] In case that the output mode is mono/stereo/binaural output
mode, the downmix is processed by the downmix processing unit 610.
In this case, the downmix processing unit 610 can be the element
playing the same role as the former downmix processing unit
130/130A/130B described with reference to FIG. 1/FIG. 2/FIG. 3.
[0121] In case that the output mode is a multi-channel mode, the
multi-channel decoder 620 generates a multi-channel output from the
mono downmix (DMX). Likewise, the multi-channel decoder 620 may be
the element playing the same role as the former multi-channel
decoder 140 described with reference to FIG. 1.
[0122] Meanwhile, if the mono downmix signal is inputted to the OTN
module 630 according to the mode selection information (MSI), the
OTN module 630 extracts a mono background object (MBO) and at least
one independent object signal (FGO) from the downmix signal. In
this case, OTN is an abbreviation of one-to-n. If one independent
object signal exists, the OTN module can have OTT (one-to-two)
structure. If two independent object signals exist, the OTN module
can have OTT (one-to-three) structure. If there exist (N-1)
independent object signals, the OTN module can have OTN
structure.
[0123] The OTN module 630 is able to use object information (OI)
and enhanced object information (EOI). In this case, the enhanced
object information (EOI) can be a residual signal generated in the
course of downmixing a background object and an independent
object.
[0124] And, the rendering unit 640 generates an output channel
signal by rendering background information (MBO) and independent
object (FGO) using mix information (MXI). In this case, the mix
information (MXI) includes the information for controlling the
background object and/or the information for controlling the
independent object. Meanwhile, multi-channel information (MI) can
be generated based on the object information (OI) and the mix
information (MXI). In this case, the output channel signal is
inputted to a multi-channel decoder (not shown in the drawing) and
can be then upmixed based on the multi-channel information.
[0125] FIG. 9 is a block diagram of an apparatus for processing an
audio signal according to a first embodiment of the present
invention for processing an enhanced object, FIG. 10 is a block
diagram of an apparatus for processing an audio signal according to
a second embodiment of the present invention for processing an
enhanced object, and FIG. 11 and FIG. 12 are block diagrams of an
apparatus for processing an audio signal according to a third
embodiment of the present invention for processing an enhanced
object.
[0126] A first embodiment relates to a mono downmix and a mono
object. A second embodiment relates to a mono downmix and a stereo
object. And, a third embodiment relates to a case of covering both
cases of the first and second embodiments.
[0127] Referring to FIG. 9, an enhanced object information encoder
710 of an audio signal encoding apparatus 700A generates enhanced
object information (EOP_x.sub.1) from a mixed audio signal, which
is a mono signal, and an object signal (obj_x.sub.1). In this case,
as one signal is generated using two signals, the enhanced object
information encoder 710 can be implemented as an OTT (one-to-two)
encoding module. In this case, the enhanced object information
(EOP_x.sub.1) can be a residual signal. And, the enhanced object
information encoder 710 generates object information (OP_x.sub.1)
corresponding to the OTT module.
[0128] An enhanced object information decoder 810 of an audio
signal decoding apparatus 800A generates an output signal
(obj_x.sub.1') corresponding to additional remix data using the
enhanced object information (EOP_x.sub.1) and the mixed audio
signal.
[0129] Referring to FIG. 10, an audio signal encoding apparatus
700B includes a first enhanced object information encoder 710B and
a second enhanced object information encoder 720B. And, an audio
signal decoding apparatus 800B includes a first enhanced object
information decoder 820B and a second enhanced object information
decoder 810B.
[0130] The first enhanced object information encoder 710B generates
a combined object and first enhanced object information (EOP_L1) by
combining two object signals (obj_x.sub.1, obj_x.sub.2) together.
In this case, the two object signals can include a stereo object
signal, i.e., a left channel signal of an object and a right
channel signal of the object. In the course of generating the
combined object, first object information (OP_L1) is generated.
[0131] The second enhanced object information encoder 720B
generates second enhanced object information (EOP_L0) and second
object information (OP_L0) using a mixed audio signal, which is a
mono signal, and the combined object.
[0132] Thus, a final signal is generated through the above two
steps. As each of the first and second enhanced object information
encoders 710B and 720B generates one signal from two signals, it
can be implemented as an OTT (one-to-two) module.
[0133] The audio signal decoding apparatus 800B performs a process
in reverse to that of the audio signal encoding apparatus 700B.
[0134] In particular, the second enhanced object information
decoder 810B generates a combined object using the second enhanced
object information (EOP_L0) and the mixed audio signal. In this
case, an audio signal can be further extracted.
[0135] And, the first enhanced object information decoder 820B
generates two objects (obj_x.sub.1', obj_x.sub.2'), which are
additional remix data, from the combined object using the first
enhanced object information (EOP_L1).
[0136] FIG. 11 and FIG. 12 show the combined structure of the first
and second embodiments. Referring to FIG. 11, if an enhanced object
is changed into mono or stereo according to a presence or
non-presence of operation of 5-1-5 or 5-2-5 tree structure of a
multi-channel encoder 705C, a downmix signal is changed into a mono
signal or a stereo signal.
[0137] Referring to FIG. 11 and FIG. 12, in case that an enhanced
object is a mono signal, a first enhanced object information
encoder 710C and a first enhanced information decoder 820C are not
operated. Functions of elements are identical to those of the same
names described with FIG. 10, respectively.
[0138] Meanwhile, in case that a downmix signal is mono, a second
enhanced object information encoder 720C and a second enhanced
information decoder 810C preferably operate as an OTT encoder and
an OTT decoder, respectively. In case that a downmix signal is
stereo, the second enhanced object information encoder 720C and the
second enhanced information decoder 810C can operate as a TTT
encoder and a TTT decoder, respectively.
[0139] According to the present invention, the above-described
audio signal processing method can be implemented in a program
recorded medium as computer-readable codes. The computer-readable
media include all kinds of recording devices in which data readable
by a computer system are stored. The computer-readable media
include ROM, RAM, CD-ROM, magnetic tapes, floppy discs, optical
data storage devices, and the like for example and also include
carrier-wave type implementations (e.g., transmission via
Internet). Moreover, a bitstream generated by the encoding method
is stored in a computer-readable recording medium or can be
transmitted via wire/wireless communication network.
INDUSTRIAL APPLICABILITY
[0140] Accordingly, the present invention is applicable to encoding
and decoding an audio signal.
[0141] While the present invention has been described and
illustrated herein with reference to the preferred embodiments
thereof, it will be apparent to those skilled in the art that
various modifications and variations can be made therein without
departing from the spirit and scope of the invention. Thus, it is
intended that the present invention covers the modifications and
variations of this invention that come within the scope of the
appended claims and their equivalents.
* * * * *